Recent research progress of two-dimensional intrinsic ferroelectrics and their multiferroic coupling

Abstract

Ferroelectric materials have become a research focus of condensed matter physics because of their electric polarization state which can be regulated by external field and has potential applications in sensors, optoelectronic devices and information memory devices. With the rapid development of microelectronic integration technology, electronic devices are becoming more and more miniaturized, integrated and multifunctional. Due to the size effect and interface effect, the traditional bulk ferroelectric materials are difficult to meet the requirements for this development. Therefore, low-dimensional ferroelectric materials have received extensive attention of the academic circle. In recent years, stable room temperature intrinsic two-dimensional ferroelectric materials have been successfully prepared. The prediction and design of new materials in theoretical method such as first principles calculation also promote the development of two-dimensional ferroelectric materials. At the same time, the multiferroic coupling effect of two-dimensional ferroelectricity, ferrovalley and magnetism can be used to realize the electronic valley polarization, electronic magnetic control and other regulatory mechanisms. The coupling of multiple degrees of freedom will produce strange physical properties such as optical selectivity of circular (linear) polarization between energy valleys and quantum spin Hall effect, which is of great significance for developing spintronics, valley electronics and optics. In this paper, the recent progress of theoretical and experimental research of new two-dimensional ferroelectric materials is introduced, and the applications of two-dimensional ferroelectric materials in two-dimensional ferroelectric devices such as ferroelectric tunnel junctions and ferroelectric diodes are presented. Secondly, the multiferroic coupling effect of two-dimensional electrically controlled ferroelectric valley and electronically controlled magnetism and their derived new physical phenomena and mechanisms are described. Finally, the rich physical connotation and broad application prospects of coupling two-dimensional ferroelectric materials with other physical properties are analyzed and discussed.